DESC:Prosthetic Hand Device

FIELD OF THE INVENTION

[001] The present invention relates to a prosthetic hand device, and more specifically to a device that provides shape adaptive gripping and a sensor-less feedback mechanism in robotic grippers

BACKGROUND

[002] In the field of prosthetics and orthotics, a number of under-actuated robotic anthropomorphic grippers/hands/hand exoskeletons are available in market which help a disabled person to grip to an object. Such grippers are controlled by a motor connected to a pulley. The fingers of the gripper are attached to the pulley through threads. The rotation of the motor causes the pulley to rotate, thereby causing the gripper to either fold or open. However, the drawback of such grippers is that a single motor is used to control all the fingers. Since the fingers are controlled by a single motor, they move by the same amount of distance as moved by the prime mover, thereby causing inadequate gripping of objects.

[003] Further, in existing under-actuated robotic anthropomorphic grippers, the fingers do not adapt to the shape of the object being grasped. This results in an inadequate gripping. In order to provide adaptive gripping, some of the under-actuated robotic anthropomorphic grippers have independent actuators attached to the fingers. However, having separate motors increases the power consumption and weight, thereby increasing the overall complexity and cost of the device. Further, as such devices are generally battery operated, it is not advisable to have high power consumption and weight.

[004] Further, in order to make a user of the prosthetic gripper/hand/exoskeleton feel the object being held, some kind of feedback mechanism is needed to sense the presence of the object and quantify the amount of pressure being exerted on the object. Existing prosthetic grippers don’t provide the feedback. If additional sensors inside the grippers leads to more power consumption and also adds to the weight of the grippers and also renders the devices structurally weak. Hence, there is a need for a system that provides a sensor-less feedback mechanism as to how much pressure is to be applied on the object to achieve the adaptive gripping.

[005] Furthermore, accessing various function/ modes of the prosthetic gripper/hand, such as wrist rotation, speed change, grip mode change, etc., requires either manual changing using buttons or by using multichannel EMG/EEG sensors. Using buttons negates the purpose of using an automated hand whereas using multichannel sensors becomes complex and not user friendly. Hence, there is a need for a system that provides a seamless experience for the user based on a gesture-based function selection.

SUMMARY OF THE INVENTION

[006] This summary is provided to introduce a selection of concepts, in a simple manner, which are further described in detailed description of the invention. This summary is neither intended to identify the key or essential inventive concept of the subject matter, nor to determine the scope of the invention.
[007] Various embodiments of the present disclosure provide a prosthetic hand device that enable the user to control grip of the prosthesis, either manually or automatically. In case of a prosthetic hand, the user is able to feel when he/she is opening, closing the gripper, the instant when an object comes in contact with the gripper, the amount of force the user is using to grip the object.
[008] Further benefits, goals and features of the present invention will be described by the following specification of the attached figures, in which components of the invention are exemplarily illustrated. Components of the devices and method according to the inventions, which match at least essentially with respect to their function, can be marked with the same reference sign, wherein such components do not have to be marked or described in all figures.
The invention is just exemplarily described with respect to the attached figures in the following.

BRIEF DESCRIPTION OF DRAWINGS

[009] The invention will be described and explained with additional specificity and detail with the accompanying figures in which:
[0010] FIG. 1 illustrates an exemplary adaptive gripping to enable a prosthetic hand device to grip an object sufficiently, in accordance with an embodiment of the present disclosure;
[0011] FIG. 2 illustrates a mechanism for moving a finger of the prosthetic hand device;
[0012] FIG. 3A illustrates a prosthetic hand device attached to an amputated hand;
[0013] FIG. 3B is a block diagram illustrating the electronic components of the prosthetic hand device;
[0014] FIG. 3C illustrates various gestures that can be performed by the prosthetic hand device;
[0015] FIG. 3D illustrates current flow during various phases of the movement of the prosthetic hand device;
[0016] FIG. 4A illustrates a first type of actuator mechanism used for controlling the movement of first through fifth fingers of the prosthetic hand device;
[0017] FIGs.4B-4M illustrate various positions of the fingers of the device based on the objects held by the fingers;
[0018] FIG. 5A illustrates a second type of actuator mechanism used for controlling the movement of first through fifth fingers of the prosthetic hand device;
[0019] FIGs.5B-5O illustrate various positions of the fingers of the device based on the objects held by the fingers.
[0020] FIGs. 6A-6D illustrate various arrangement of pulleys of the second type of actuator mechanism;
[0021] FIG. 7A illustrates a third type of actuator mechanism used for actuating the fingers of the prosthetic hand device; and
[0022] FIGs. 7B-7M illustrate various positions of the fingers of the device based on the objects held by the fingers.
[0023] Furthermore, the figures may show only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the figures with details that will be readily apparent to those skilled in the art having the benefit of the description herein.

DETAILED DESCRIPTION OF INVENTION

[0024] For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the figures and specific language will be used to describe them. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Such alterations and further modifications in the illustrated system, and such further applications of the principles of the invention as would normally occur to those skilled in the art are to be construed as being within the scope of the present invention.

[0025] It will be understood by those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the invention and are not intended to be restrictive thereof.

[0026] The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such a process or method. Similarly, one or more sub-systems or elements or structures or components preceded by "comprises... a" does not, without more constraints, preclude the existence of other, sub-systems, elements, structures, components, additional sub-systems, additional elements, additional structures or additional components. Appearances of the phrase "in an embodiment", "in another embodiment" and similar language throughout this specification may, but not necessarily do, all refer to the same embodiment.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention belongs. The system, methods, and examples provided herein are only illustrative and not intended to be limiting.

[0028] FIG. 1 illustrates an exemplary adaptive gripping 100 to enable a prosthetic hand device 102 to grip an object sufficiently, in accordance with an embodiment of the present disclosure. The prosthetic hand device 102 may be hereinafter also referred to as hand exoskeleton 102. In order to provide a sufficient grip, that is irrespective of shape and orientation, each finger of the prosthetic hand device 102 must stop at different positions.

[0029] FIG. 2 illustrates a mechanism for moving a finger of the prosthetic hand device 102. Each finger 202 of the prosthetic hand device 102 is attached to an actuator 204 (pulley 204) coupled to a motor (not shown). When the motor rotates in clockwise direction, the thread wraps around the pulley 204, hence pulling respective thread down. Since the finger 202 is fixed at the base, it bends forward and hence closes the hand.

[0030] FIG. 3A illustrates a prosthetic hand device 302 (similar to the prosthetic hand device 102) attached to an amputated hand 304.

[0031] The prosthetic hand device 302 is in form of a prosthetic socket 304, that includes an actuator sensor 306, an actuator system 308 operating based on an actuation signal of the actuator sensor 306, and a feedback actuator 310 operating based on the feedback from the actuator system 308. The actuator system 308 receives sensor data from the actuator sensor 306 to operate the fingers of the prosthetic device 302, and provides control signals to the feedback actuator 310 to behave in a specific way.

[0032] The actuator sensor 306 includes an array of one or more sensors for sensing information like touch, grip, vibration, force, temperature, texture of an object to be held as well as its surrounding. Examples of the array of one or more sensors include, but not limited to, force, pressure, resistive, capacitive, piezo, dielectric elastomer, bio-potential such as Electromyography (EMG) or Electroencephalogram (EEG).

[0033] The feedback actuator 310 includes an array of one or more actuators or indicators for either interacting with the user’s one or more than one senses (such as touch, lights, sounds, smell etc.) or controlling the Real World System. The array of one or more actuators include, but not limited to, force, touch, squeeze, electric impulses, vibration, etc. Examples of the feedback actuator 310 include vibration motors, linear motors and solenoids.

[0034] Referring to FIG. 3B, the actuator system 308 includes a power supply 312, a current sensor 314, a controller 316, an actuator 318, an actuation mechanism 320, and a feedback actuator driver 322. The power supply 312 provides power for operating the current sensor 314 and the controller 316. Examples of the power supply 312 includes a battery.

[0035] The actuator 318 is a prime mover like a motor or a linear motor, which is physically connected to the actuation mechanism 320. Examples of the actuation mechanism 320 includes a combination of bars, a combination of pulleys, and a combination of differential drive mechanisms, that are connected to the fingers of the hand prosthetic device 302 to move them to facilitate adaptive gripping of an object.

[0036] The actuator sensor 306 detects one or more gestures performed by the gripper/hand and communicates the detected gestures to the controller 316. The actuator sensor 306 may include an in-built 3-axis Gyroscope and a 3-axis accelerometer. FIG. 3C illustrates various gestures that can be performed by the prosthetic hand device 302, in accordance with an embodiment of the present disclosure. The gestures shown in the FIG. 3C are as follows:
• Gesture A: Waving motion on Y-Z Plane about the elbow
• Gesture B: Circular motion about the Z-axis along the X-Y plane
• Gesture C: Waving motion on X-Z plane about the elbow
• Gesture D: Light tapping on a hard surface along the Y-axis. It can have two sub gestures- single tap and double tap.

[0037] The controller 316 receives the detected gestures from the actuator sensor 306 and provides following functionalities to the user based on the detected gestures:
I. Wrist rotation - unlocked/ locked
II. Grip force increase/ decrease
III. Grip Speed increase/ decrease
IV. Toggle grip modes in multi-actuator devices
V. Change sensor sensitivity

[0038] However, the above-mentioned functions can be accessed only when the hand is in open position, thereby avoiding any false trigger during a gripping action. Using gesture-based function selection can create a seamless experience for the user.

[0039] The current sensor 314 includes one or more sensors for sensing current flow to the actuator 318 to determine amount of pressure being exerted on an object being gripped by the prosthetic hand device 302 (An exemplary gripping of the object has been explained with reference to FIG.1). In order to make the user of the prosthetic hand device 302 feel the object being held, the current sensor 314 measures the amount of current flowing through the actuator 318 and communicates the measured amount to the controller 316. The controller 316 determines the pressure being exerted on the object based on the current flowing to the actuator 318. The current can be measured across the actuator terminals by using any of the popular current sensing mechanisms such as, but not limited to, using a series resistor, a hall effect sensor, etc.

[0040] Further, in order to maintain the grip of the object, the actuator 318 needs to hold its position at a particular angle. In absence of any mechanical locking, the actuator 318 draws equivalent amount of current in order to provide sufficient torque for the grip. The current in the actuator 318 rises with increase in pressure exerted on the object. Hence, current is directly proportional to the pressure exerted.

[0041] FIG. 3D illustrates current flow during various phases of the prosthetic hand movement, in accordance with the present disclosure. Based on the current drawn during different events, such as opening and closing of the gripper/hand and with and without an object, a possible threshold can be set for pressure detection. Once the threshold is crossed, the presence of object is detected. Therefore, higher the value of current above the threshold, the more pressure is being exerted on the object. The feedback actuator driver 322 receive inputs from the controller 316, and enable the feedback actuator 310 to move based on displacement, amplitude, and frequency or a combination of the above. Hence, the current flowing through the actuator 318 is used as a feedback by the controller 316 to determine the amount of pressure being exerted on the object being held. Based on the feedback, the controller 316 provides control signals to the feedback actuator driver 322 to enable the feedback actuator 310 to notify the user to either stop applying more pressure on the object or to apply more pressure on the object so as to provide adequate gripping. The user can be notified in the form of, but not limited to, pulsating vibrations, electrical stimulation, heating patches, pressure bands, etc. As shown in FIG. 3A, the feedback actuator 310 can be used to relay the pressure information, and is placed on the residual limb of the user. In an embodiment of the present disclosure, the back-current, back pressure, or back-emf of the array of one or more actuators 318 can be used as a feedback signal by the controller 316 to help in adequate gripping of the object, thereby eliminating the use of additional sensors in the system.

[0042] FIG. 4A illustrates a first type of actuator mechanism 402 used for controlling the movement of first through fifth fingers of the prosthetic hand device 400 (similar to the device 302) to move the fingers downwards. The first type of actuator mechanism 402 includes first and second bars A and B connected to an actuator 404 such as a motor, through tendons/threads that may be extensible, inextensible or a composite. The actuator 404 may be hereinafter also referred to as motor 404. The first bar A is connected to two fingers, such as second and fourth fingers. The second bar B is connected to two fingers, such as third and fifth fingers. The first and second bars A and B are connected to the fingers through inextensible threads. The motor 404 is directly connected to the thumb through a thread that may be extensible, inextensible or a composite. The actuator 404 is operated by the controller (not shown) similar to the controller 316 based on actuation signals generated by the actuator sensor 306. move the tendons which in turn move respective fingers in downward direction. In an embodiment of the present disclosure, when one of the fingers gets obstructed, the corresponding bar pivots about the center so as to allow displacement for the unobstructed finger, thereby providing adaptive gripping for the device.

[0043] FIGs.4B-4M illustrate various positions of the fingers of the device 400 based on the objects held by the fingers.

[0044] In FIG.4B, as the motor 404 rotates, both bars A and B move down by distance dC, and second, third, fourth and fifth fingers move down from an initial open position to become folded. The thumb may be configured to fold after a predetermined amount of thread is folded upon rotation of the actuator 404. Also, as the second to fifth fingers fold completely upon rotation of the motor 404, it implies that there is no obstruction for the second to fifth fingers.

[0045] In FIG.4C, as the motor 404 rotates, bar B tilts by distance dC in the direction indicated in figure which results in bending of the third finger. Also, only as the third finger fold upon rotation of the motor 404, it implies that there is an object held by the second, fourth and fifth fingers.

[0046] In FIG.4D, as the motor 404 rotates, the thumb bends, bar A tilts by distance dC in the direction indicated in figure which results in bending of the fifth finger, bar B moves down by distance dC and as a result third and fourth fingers get folded. Also, as the second finger does not fold upon rotation of the motor 404, it implies that there is an obstruction for the second finger.

[0047] In FIG.4E, as the motor 404 rotates, the thumb bends, bar A tilts by distance dC in the direction indicated in figure which results in bending of the second finger, bar B moves down by distance dC and as a result the third and fingers gets folded. Also, as the fifth finger does not fold upon rotation of the motor 404, it implies that there is an obstruction for the fifth finger.

[0048] In FIG. 4F, as the motor 404 rotates, bar A tilts by distance dC in the direction indicated in figure which results in bending of the fifth finger, bar B moves down by distance dC and as a result, the third and fourth fingers get folded. Also, as the thumb and second finger does not fold upon rotation of the motor 404, it implies that there is an obstruction between the thumb and the second finger.

[0049] In FIG. 4G, as the motor 404 rotates, bar B moves down by distance dC which results in bending of the third and fourth fingers. Also, as the first, second, and fifth fingers do not fold upon rotation of the motor 404, it implies that there is an obstruction for the first, second and fifth fingers.

[0050] In FIG.4H, as the motor 404 rotates, bar B and bar A tilt by distance dC in the direction indicated in figure which results in bending of the fourth and fifth fingers respectively. Also, as the first, second and third fingers do not fold upon rotation of the motor 404, it implies that there is an obstruction for the first, second and third fingers.

[0051] In FIG. 4I, as the motor 404 rotates, bar A tilts by distance dC in the direction indicated in figure which results in bending of the second finger. Also, as the third, fourth and fifth fingers do not fold upon rotation of the motor 404, it implies that there is an obstruction for the third, fourth and fifth fingers.

[0052] In FIG.4J, there is no rotation of motor 404 hence there is no movement in fingers.

[0053] In FIG.4K, as the motor 404 rotates, bar A tilts by distance dC in the direction indicated in figure which results in bending of the second finger, bar B moves down by distance dC and as a result the third and fourth fingers get folded. Also, as the fifth finger does not fold upon rotation of the motor 404, it implies that there is an obstruction for the fifth finger.
[0054] In FIG.4L, as the motor 404 rotates, bar B tilts by distance dC in the direction indicated in figure which results in bending of the fourth finger. Also, as the fourth finger does not fold upon rotation of the motor 404, it implies that there is an obstruction for the fourth finger.
[0055] In FIG.4M, as the motor 404 rotates, bar A and B moves down by distance dC which results in bending of the second, third, fourth and fifth fingers.
[0056] FIG. 5A illustrates a second type of actuator mechanism 502 used for controlling the movement of first through fifth fingers of the hand prosthetic device 500. The second type of actuator mechanism 502 includes first and second pulleys A and B connected to an actuator 504. The actuator 504 is hereinafter referred to as a motor 504. Also, FIG. 5A illustrates an open position of the fingers of the hand prosthetic device 500. The thumb is directly connected to the motor 504. The first pulley A is connected to the second and fourth fingers, and the second pulley B is connected to two fingers, such as third and fifth fingers. The motor 504 is directly connected to the thumb. The threads connecting the fingers to the first and second pulleys A and B are made from inextensible material, whereas the threads connecting the first and second pulleys A and B to the motor 504 maybe extensible or inextensible or a composite of two.
[0057] In an embodiment of the present disclosure, both ends of each pulley A and B are connected to two fingers using a thread, one at each end. When the thread attached to pulley such as pulley A is pulled downward, the second and fourth fingers bend to create a grip. In such a case, displacement in both the fingers is same. But when the second finger gets obstructed and it doesn’t move, the pulley action comes into play. The pulley A slides along the thread, rotating about its own axis, thereby allowing the fourth finger to bend. Hence, the displacement in both the fingers is different. Hence, all the fingers can move at different angles, thereby providing adaptive grip for the device. Thus, in such a case, different displacement of all the fingers of the prosthetic gripper/hand can be achieved so as to provide a strong grip of an object, regardless of its shape and size.
[0058] FIGs.5B-5O illustrate various positions of the fingers of the device 500 based on the objects held by the fingers.

[0059] In FIG.5B, as the motor 504 rotates, pulleys A and B are displaced downwards by distance dC (i.e diameter of Pulley C) resulting in bending of the second and fifth fingers caused by displacement of pulley A and bending of third and fourth fingers caused by displacement of pulley B.

[0060] In FIG.5C, as the motor 504 rotates in the direction as shown in figure, the pulley B rotates in anti-clockwise direction resulting in bending of the third finger.
[0061] In FIG.5D, as the motor 504 rotates in the direction as shown in figure, the pulley B rotates in anti-clockwise direction resulting in bending of the third, fourth and fifth fingers.
[0062] In FIG.5E, as the motor 504 rotates, the thumb gets closed, pulley A rotates in anti - clockwise direction resulting in bending of the second finger and the pulley B moves down by distance dC from its initial open position resulting in bending of the third and fourth fingers.
[0063] In FIG.5F, as the motor 504 rotates, the pulley A rotates in clockwise direction resulting in bending of the fifth finger and the pulley B moves down by distance dC from its initial open position resulting in bending of the third and fourth fingers.
[0064] In FIG.5G, as the motor 504 rotates, the pulley B moves down by distance dC from its initial open position resulting in bending of the third and fourth fingers.
[0065] In FIG.5H, as the motor 504 rotates, the pulley A rotates in clockwise direction resulting in bending of the fifth finger and the pulley B rotates in clockwise direction resulting in bending of the fourth finger.
[0066] In FIG.5I, as the motor 504 rotates, the pulley A rotates in anti - clockwise direction resulting in bending of the second finger.
[0067] In FIG.5J, the motor 504 does not rotate, hence there is neither the rotations of pulleys A and B nor the displacement of pulleys A and B from their initial positions.
[0068] In FIG.5K, as the motor 504 rotates, the pulley A rotates in anti -clockwise direction resulting in bending of the second finger and the pulley B moves in downward direction by distance dC from its initial position.
[0069] In FIG.5L, as the motor 504 rotates, the pulley B rotates in clockwise direction resulting in bending of the fourth finger.
[0070] In FIG.5M, no pulley rotates hence there is no movement in fingers.
[0071] In FIG.5N,as the motor 504 rotates, the thumb gets closed, pulley A rotates in clockwise direction resulting in bending of the fifth finger and the pulley B rotates in clockwise direction resulting in bending of the fourth finger.
[0072] In FIG.5O, as the motor 504 rotates, the first finger gets closed. The pulleys A and B are displaced downwards by distance dC resulting in bending of the second and fifth fingers caused by displacement of pulley A and the bending of the third and fourth fingers caused by displacement of pulley B.
[0073] It will be apparent to one of ordinary skill in the art, that although the second actuator mechanism 502 is shown to include two similar pulleys, the second actuator mechanism 502 may include more than two similar or dissimilar pulleys, as shown with reference to FIGs. 6A-6D. The movable pulley system can be arranged to form a compound arrangement of pulleys so as to provide an adaptive grip for the device.
[0074] FIG. 7A illustrates a third type of actuator mechanism 702 used for actuating the fingers of the prosthetic gripper/hand device 700.

[0075] The third type of actuator mechanism 702 is a type of differential gear mechanism that includes gear heads A, B, C and D, gears 1, 2, 3, 4, 5, 6, 7, 8 and 9. The gear head A is coupled to the second finger, the gear head B is coupled to the third finger, the gear head C is coupled to the fourth finger, and the gear head D is coupled to the fifth finger and the first finger is directly coupled to a pulley E of an actuator 704 through extensible, inextensible or composite threads. The actuator 704 may be hereinafter referred to as motor 704. The pulley E rotates when the actuator 704 rotates. The rotation of the pulley E causes the rotation of the gear 9, which further causes the rotation of gears 4 and 8. The rotation of the fourth gear rotates gears 1 and 3 which causes movement the second and third fingers, and the rotation of the eighth gear rotates gears 5 and 7 which causes the movement of the fourth and fifth fingers. The main advantage of this mechanism is that the entire power is transferred to the moving finger, thereby making it the most efficient method.

[0076] In FIG. 7B, as the motor 704 rotates, pulley E and gear 9 rotates with same speed. Gear 9 is connected to gear 4 and 8 which results in rotation of both the gears 8 and 4. Gear 4 is connected to gear 2 which is further connected to gear 1 and 3. Hence when gear 4 rotates it causes rotation of gear 2 which further causes rotation of gears 1 and 3. The second and third fingers are connected to the gear bands A and B, and rotate when the gears 1 and 3 rotate. Also, gear 8 is connected to gear 6 which is further connected to gear 5 and 7. Hence when gear 8 rotates, it results in rotation of gear 6 which further causes rotation of gears 5 and 7, and thereby rotation of the fourth and fifth fingers through the gear bends C and D.

[0077] In FIG. 7C, as the motor 704 rotates, pulley E and gear 9 rotates with same speed. Rotation of gear 9 causes rotation of gears 4 and 8. Rotation of gear 4 causes rotation of gear 2 which further causes rotation of gears 1 and 3. But as there is obstruction to the finger 2, the rotation of gear 1 stops which leads to no movement of finger 2. Finger 3 bends. On the other hand gear 8 is connected to gear 6 which is further connected to gear 7 and 5. But due to obstruction to fingers 4 and 5, there is no rotation of gears 5,6,7, and hence the fingers do not bend.

[0078] In FIG.7D, the pulley E rotates with the motor 704, the finger 1 connected to it via string is bent. The gear 9 which also connected to pulley E rotates which causes rotation of gears 4 and 8. As gear 4 rotates, gear 2 connected to it rotates and it further rotates gear 1 and 3 which are connected to fingers 2 and 3. Finger 2 is obstructed hence it does not bend but finger 3 bends. On the other hand when gear 8 rotates, there is rotation of gear 6 which further rotates gear 7 and 5. Gears 7 and 5 are connected to fingers 4 and 5 by strings and hence they cause bending of fingers 4 and 5.

[0079] In FIG.7E, as pulley E rotates, the finger 1 connected to it via string is bent. The gear 9 which is also connected to pulley E rotates which causes rotation of gears 4 and 8. When gear 4 rotates, it causes rotation of gear 2 which further causes rotation of gears 1 and 3. Hence fingers 2 and 3 get bent. On the other hand, gear 8 is connected to gear 6 which is further connected to gear 7 and 5. Gears 7 and 5 are connected to fingers 4 and 5 respectively. Finger 4 bends but finger 5 do not bend as it is obstructed.

[0080] In FIG.7F, as pulley E rotates with the motor 704, gear 9 rotates which causes rotation of gears 4 and 8. As gear 4 rotates, gear 2 connected to it rotates and it further rotates gear 1 and 3 which are connected to fingers 2 and 3. Finger 2 is obstructed hence it does not bend but finger 3 bends. On the other hand when gear 8 rotates, there is rotation of gear 6 which further rotates gear 7 and 5. Gears 7 and 5 are connected to fingers 4 and 5 by strings and hence they cause bending of fingers 4 and 5

[0081] In FIG. 7G, as the pulley E rotates with the motor 704, gear 9 rotates which causes rotation of gears 4 and 8. As gear 4 rotates, gear 2 connected to it rotates and it further rotates gear 1 and 3 which are connected to fingers 2 and 3. Finger 2 is obstructed hence it does not bend but finger 3 bends. Further, finger 4 bends but finger 5 does not bend as it is obstructed.

[0082] In FIG. 7H, as the pulley E rotates with the motor 704, gear 9 rotates which causes rotation of gears 4 and 8. As gear 4 rotates, gear 2 connected to it rotates and it further rotates gear 1 and 3 which are connected to fingers 2 and 3. But as fingers 2 and 3 are obstructed, they do not bend. Gears 7 and 5 are connected to fingers 4 and 5 by strings and hence they cause bending of fingers 4 and 5.

[0083] In FIG.7I, as the pulley E rotates with the motor 704, rotation of gear 9 causes rotation of gear 4 and 8 which are connected to it. The rotation of gear 4 causes rotation of gear 2 which further causes rotation of gears 1 and 3. But as there is obstruction to the finger 3, the rotation of gear 3 stops which leads to no movement of finger 3. On the other hand, gear 8 is connected to gear 6 which is further connected to gear 7 and 5. But due to obstruction to fingers 4 and 5, there is no rotation of gears 5,6,7 and hence the fingers do not bend.

[0084] In FIG.7J, there is no rotation of the motor 704, hence there is no movement in fingers.

[0085] In FIG.7K, as the pulley E rotates with the motor 704, gear 9 rotates which causes rotation of gears 4 and 8. When gear 4 rotates it causes rotation of gear 2 which further causes rotation of gears 1 and 3. Hence fingers 2 and 3 are bent. Further, finger 4 bends but finger 5 do not bend as it is obstructed.

[0086] In FIG.7L, as the pulley E rotates with the motor 704, gear 9 rotates which causes rotation of gears 4 and 8. As gear 4 rotates, gear 2 connected to it rotates and it further rotates gear 1 and 3 which are connected to fingers 2 and 3. But as fingers 2 and 3 are obstructed, they do not bend. On the other hand, finger 4 bends but finger 5 is obstructed hence it does not bend.

[0087] In FIG.7M, as the motor rotates, gear 9 rotates, to cause slight bending of fingers. The fingers may not bend completely due to obstruction.

[0088] While specific language has been used to describe the invention, any limitations arising on account of the same are not intended. As would be apparent to a person skilled in the art, various working modifications may be made to the method in order to implement the inventive concept as taught herein.

[0089] The figures and the foregoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, order of processes described herein may be changed and are not limited to the manner described herein. Moreover, the actions of any flow diagram need not be implemented in the order shown; nor do all of the acts need to be necessarily performed. Also, those acts that are not dependent on other acts may be performed in parallel with the other acts. The scope of embodiments is by no means limited by these specific examples.
,CLAIMS:
1. A prosthetic hand device, comprising:
an actuator sensor configured to detect one or more gestures performed by the prosthetic hand device, and generate an actuation signal based on the detected one or more gestures;
an actuator system coupled to the actuator sensor, and comprising:
an actuator mechanism operably connected to the fingers of the prosthetic device through respective threads to enable the fingers to stop at different positions to perform adaptive gripping of an object;
an actuator operably connected to the actuator mechanism to drive the actuator mechanism;
a controller connected to the actuator, and configured to:
operate the actuator based on the actuation signal generated by the actuator sensor; and
a current sensor configured to sense current flowing across the actuator to determine a pressure being exerted on the object gripped by the fingers,
wherein the controller is configured to generate a control signal based on the sensed current; and
a feedback actuator configured to generate a feedback signal for the user based on the control signal.

2. The prosthetic hand device as claimed in claim 1, wherein the actuator sensor includes at least one of: a force sensor, a pressure sensor, a resistive sensor, a capacitive sensor, a piezo sensor, a dielectric elastomer, an Electromyography (EMG) sensor, and an Electroencephalogram (EEG) sensor.

3. The prosthetic hand device as claimed in claim 1, wherein the feedback actuator includes an array of one or more actuators and the feedback signal is selected from at least one or a combination of: a pulsating vibration, an electrical stimulation, a heating signal, and a pressure signal.

4. The prosthetic hand device as claimed in claim 1, wherein the actuator mechanism includes a compound arrangement of pulleys, in that a first pulley is operably coupled to two fingers, and a second pulley is operably coupled to other two fingers, the first and second pulleys are operably coupled to the actuator, and a thumb is operably coupled to the actuator, wherein the threads connecting the fingers to the first and second pulleys are made from an inextensible material, and wherein the threads connecting the first and second pulleys to the actuator are made from at least one of: an extensible material, an inextensible material, and a combination of the extensible and inextensible material.

5. The prosthetic hand device as claimed in claim 1, wherein the compound arrangement of pulleys enable each finger to move at a different angle and a different displacement with respect to other, to provide a strong grip of the object, irrespective of a shape and size of the object.

6. The prosthetic hand device as claimed in claim 1, wherein the actuator mechanism includes a compound arrangement of bars, in that a first bar is connected to two fingers, and a second bar is connected to other two fingers, wherein the first and second bars are connected to the fingers through inextensible threads, and the first and second bars are connected to the actuator through a material selected from at least one of: extensible, inextensible and a composite, wherein when a finger gets obstructed, the corresponding bar pivots about a center to enable displacement for unobstructed finger.

7. The prosthetic hand device as claimed in claim 1, wherein the actuator mechanism includes a differential drive mechanism including a compound arrangement of the gears, wherein the differential drive mechanism includes first, second, third and fourth gear heads operably coupled to first, second, third and fourth fingers respectively, a pulley operably coupled to the actuator and to the thumb, a first gear operably coupled to the pulley, second and third gears operably coupled to the first gear, fourth and fifth gears operably coupled to the second gear and to the first and second gear heads respectively, and sixth and seventh gears operably coupled to the third fear and to the third and fourth gear heads respectively.

8. The prosthetic hand device as claimed in claim 7, wherein the rotation of the pulley causes the rotation of the first gear, which causes the rotation of the second and third gears, and wherein the rotation of the second gear rotates fourth and fifth gears to move first and second fingers respectively, and the rotation of the third gear rotates sixth and seventh gears to move third and fourth fingers respectively.

9. The prosthetic hand device as claimed in claim 1, wherein the actuation system further comprises a back-current sensor, a back pressure, and a back-emf sensor for enabling the controller to generate the control signal, and the feedback actuator for generating the feedback signal for the user based on the control signal.

10. The prosthetic hand device as claimed in claim 9, wherein the feedback signal enables controlling grip of corresponding prosthesis, either manually or automatically, and facilitates the user to feel an opening and closing of the device, a time instant at which an object comes in contact with the device, and an amount of force exerted by the user to grip the object.